Wall Street went into a deep slump Wednesday, falling so far and so fast that the Dow Jones industrial average officially tipped into a bear market, ending a record 11-year stock rally.

The bear market reflects a 20 percent fall from record highs, which the Dow hit less than a month ago, and came after the coronavirus officially became a pandemic. The World Health Organization’s declaration Wednesday reflected its alarm that countries aren’t working quickly and aggressively enough to fight the disease covid-19, caused by the coronavirus.

The Dow — already deep in the red for the day — tumbled nearly 1,500 points after the WHO announcement. It closed at 23,553, a nearly 6 percent decline on the day. The Standard & Poor’s 500 index flirted with bear territory before closing just above the mark at 2,741, a 4.9 percent fall for the session. The Nasdaq composite tumbled 4.7 percent to 7,952. All three indexes are in negative territory for the year.

“Bear markets are ugly,” said Michael Farr, president of investment firm Farr, Miller & Washington. “They’re painful and they all last too long. Sadly, it seems that a new one is just getting started.”

All 11 S&P stock market sectors turned negative on Wednesday. Industrials, financials, energy and real estate fared the worst, while the health sector was the least hurt. All 30 Dow components were deeply negative. Boeing felt the brunt of the Dow sell-off, shedding 18 percent of its value.

“Markets will continue to tumble,” said Howard Yu, LEGO professor and director of the advanced management program at the Lausanne, Switzerland-based IMD business school in an email. “We can’t predict yet when they might bottom out, because we don’t know how long the global virus will spread.”

Asian markets and U.S. stock futures fell sharply on Thursday after an Oval Office speech by President Trump late Wednesday banning travel from Europe for 30 days triggered fresh alarm among investors. S&P futures were down 4.1 percent.

Markets had ended on a high note Tuesday after a day of big swings, with the Dow climbing more than 1,100 points on word the White House was making progress on economic measures to help industries and workers hurt by the coronavirus, including plans to cut payroll taxes, relieve hourly workers and offer targeted help for the airline, cruise and hotel industries. The gains helped ease some of the pain from Monday’s free-fall, which sent U.S. markets tumbling more than 7 percent. The sudden, sharp market drop triggered a halt to trading for 15 minutes.

White House officials have invited top Wall Street executives to meet this week as the coronavirus outbreak creates enormous strains on the U.S. economy, The Washington Post reported Tuesday. The agenda for the meeting and the invitation list could not immediately be ascertained.

The White House and Congress, meanwhile, are at odds over what type of economic rescue package to assemble. The Trump administration has pushed the idea of new tax cuts and delayed tax filings as a way to boost the economy, as well as expanding sick leave benefits and helping the airline, hotel, and cruise industries. Democrats are moving ahead in the House of Representatives with a plan to expand unemployment insurance, provide more sick leave, and assure food benefits are available for people who lose their jobs and need emergency assistance.

“The public’s reaction to the virus literally has the potential to shut down the economy with travel interrupted and business meetings canceled,” Chris Rupkey, chief financial economist at MUFG Union Bank, wrote in commentary Wednesday. “The wheels of the economy can’t continue to turn as fast if the whole country avoids social interaction and tries to live online through the Internet. With less store traffic, merchants may have to actually cut prices instead of raising them.”

Saudi Arabia on Wednesday announced its first oil production increase in a decade, with state oil giant Saudi Aramco moving to ramp up production to a record 13 million barrels per day, vs. roughly 12 million barrels. The company did not give a timeline for the action but was responding to similar reports Tuesday out of Russia.

Oil prices, which had recovered somewhat after skidding 25 percent Monday, tumbled after the announcement. Brent crude, the global oil benchmark, sank 4 percent to about $35.74 per barrel.

The threat of oil wars exacerbated investor panic about the coronavirus, as confirmed U.S. cases surpassed 1,000 and deaths exceeded 30. The pneumonia-like disease has spread to every continent save Antarctica since it was first detected in China late last year, sickening more than 120,000 people and claiming more than 4,300 lives.

Government officials and businesses are taking sweeping action to curtail community spread through social distancing. Gold prices gave up ground following a recent run-up. Oil was down as the markets remain oversupplied with no relief in sight. The yield on the 10-year U.S. Treasury note, a critical tool of global finance, closed up slightly at 0.878 percent. Yields fall as demand pushed bond prices up.

“The bond market has yet to shrug off coronavirus fears while stocks are behaving much more erratically,” Danielle DiMartino Booth, CEO and chief strategist at Quill Intelligence, told The Post in an email. “The fear factor won’t dissipate until the public has better clarity on the extent of the virus’ spread here in the United States.”

Washington state is prohibiting gatherings of more than 250 people in the Seattle area, one of the most drastic moves yet to contain the spread of the new coronavirus. Colleges nationwide have canceled in-person classes, and some, including the Massachusetts Institute of Technology and the University of Dayton in Ohio, have ordered students to vacate dorms.

Officials in New York created a one-mile containment zone in New Rochelle, a suburb of New York City where the state’s outbreak has been concentrated. Schools, places of worship and other large gathering spots inside the area will be closed for two weeks, as National Guard troops help with disinfection and food delivery.

“The lockdown of Italy and quarantining in New Rochelle, where I went to high school, are raising fears about a worldwide recession even though the news out of China and South Korea is improving,” said Ed Yardeni, president of Yardeni Research.

Yu, in Switzerland, said “if New York City locks down like Wuhan … the global crash we’d see then would dwarf what we’ve encountered in recent days.”

European markets got a bump Wednesday after the Bank of England slashed interest rates to a record low of 0.25 percent to cushion the British economy from coronavirus fallout. The boost was well-received but the celebration short-lived, with Britain’s FTSE 100 and Europe’s benchmark Stoxx 600 ending Wednesday to the downside.

“A rate cut is unlikely to be enough on its own to stop the UK from experiencing a significant economic dent,” said Russ Mould, investment director at AJ Bell, in commentary Wednesday. “Low borrowing rates won’t necessarily get worried consumers spending again if they are cautious about going outdoors or are even forced to stay inside because of coronavirus-related issues.”

The Federal Reserve’s first emergency rate cut since the financial crisis got a frosty reception from investors last week, and the White House is considering a variety of policy changes to blunt the coronavirus impact on American industries, including a payroll tax cut and paid sick leave. President Trump is also considering federal assistance for oil and natural gas producers that have been hit by plummeting oil prices, The Post reported Tuesday.

Wall Street offered suggestions to the Federal Reserve and lawmakers for relief from the virus. PIMCO’s U.S. economist Tiffany Wilding said in a blog post that Federal Reserve rate cuts “alone won’t be the panacea” for cushioning the economic fallout from the coronavirus.

“A more useful policy response would be the revival of some of the Fed’s crisis-era targeted lending operations,” Wilding wrote. “Or if Congress, in addition to increasing funding for the health care sector, set up targeted programs to support businesses — especially small and midsized businesses — and consumers facing cash flow disruptions related to social distancing or quarantines.”